Good 1st PDE book for self study
I am an undergraduate student in applied mathematics, and I will be studying PDEs this Fall semester. I decided to get a few steps ahead of the class and downloaded a few articles about the subject, since it is still too early to tell which book we will be using (and the professor has not yet been decided), but the things I found proved to be too esoteric a level for me to understand the least: most of the concepts they make heavy use of revolve around concepts my university does not even teach at the undergraduate level, such as measure theory and higher-level analysis.
I took a course in ODEs, and I loved it. I got as far as to cover a few things regarding Fourier transforms and simple systems. I feel that I am at a very low level of mathematical maturity, however, but I am more than determined to improve as much as I can.
What are some good sources to learn PDEs that you guys know of, and that are not at the level of Einstein's equations? Thanks in advance!